serial: 8250_lpss: set PCI master only for private DMA

There is no need to set PCI bus mastering when device is not doing any DMA.
Though on Intel Quark DMA is a part of UART IP and thus shares same device in
Linux kernel.

Enable bus mastering only for Quark case.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>